Friday, April 24, 2009

Atomic Structure

  • When forming cations, the 4s electrons will be lost first before the 3d
    electrons, even though 4s orbital is filled before the 3d orbital.

WHY?

=>The 3d orbital penetrates the electron density in the 4s orbital
considerably, thus shielding the 4s electrons from the attraction of the
nucleus and causing them to be easily lost.

=> The 3d subshell is closer to the nucleus. Once occupied by electrons,
it repels the 4s electrons even further from the nucleus and up to a higher
energy level.

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